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            <div><h4 class="title">
                <a name="asio.reference.read.overload11"></a><a class="link" href="overload11.html"
                                                                title="read (11 of 16 overloads)">read (11 of 16
                overloads)</a>
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    <p>
        Attempt to read a certain amount of data from a stream before returning.
    </p>
    <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span>
    <span class="keyword">typename</span> <a class="link" href="../SyncReadStream.html"
                                             title="Buffer-oriented synchronous read stream requirements">SyncReadStream</a><span
                class="special">,</span>
    <span class="keyword">typename</span> <span class="identifier">Allocator</span><span class="special">,</span>
    <span class="keyword">typename</span> <a class="link" href="../CompletionCondition.html"
                                             title="Completion condition requirements">CompletionCondition</a><span
                class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span
                class="identifier">read</span><span class="special">(</span>
    <span class="identifier">SyncReadStream</span> <span class="special">&amp;</span> <span
                class="identifier">s</span><span class="special">,</span>
    <span class="identifier">basic_streambuf</span><span class="special">&lt;</span> <span
                class="identifier">Allocator</span> <span class="special">&gt;</span> <span class="special">&amp;</span> <span
                class="identifier">b</span><span class="special">,</span>
    <span class="identifier">CompletionCondition</span> <span class="identifier">completion_condition</span><span
                class="special">);</span>
</pre>
    <p>
        This function is used to read a certain number of bytes of data from a
        stream. The call will block until one of the following conditions is true:
    </p>
    <div class="itemizedlist">
        <ul class="itemizedlist" type="disc">
            <li class="listitem">
                The supplied buffer is full (that is, it has reached maximum size).
            </li>
            <li class="listitem">
                The completion_condition function object returns 0.
            </li>
        </ul>
    </div>
    <p>
        This operation is implemented in terms of zero or more calls to the stream's
        read_some function.
    </p>
    <h6>
        <a name="asio.reference.read.overload11.h0"></a>
        <span><a name="asio.reference.read.overload11.parameters"></a></span><a class="link"
                                                                                href="overload11.html#asio.reference.read.overload11.parameters">Parameters</a>
    </h6>
    <div class="variablelist">
        <p class="title"><b></b></p>
        <dl>
            <dt><span class="term">s</span></dt>
            <dd><p>
                The stream from which the data is to be read. The type must support
                the SyncReadStream concept.
            </p></dd>
            <dt><span class="term">b</span></dt>
            <dd><p>
                The <a class="link" href="../basic_streambuf.html" title="basic_streambuf"><code class="computeroutput"><span
                    class="identifier">basic_streambuf</span></code></a> object into
                which the data will be read.
            </p></dd>
            <dt><span class="term">completion_condition</span></dt>
            <dd>
                <p>
                    The function object to be called to determine whether the read operation
                    is complete. The signature of the function object must be:
                </p>
                <pre class="programlisting"><span class="identifier">std</span><span class="special">::</span><span
                        class="identifier">size_t</span> <span class="identifier">completion_condition</span><span
                        class="special">(</span>
  <span class="comment">// Result of latest read_some operation.</span>
  <span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span
                            class="identifier">error_code</span><span class="special">&amp;</span> <span
                            class="identifier">error</span><span class="special">,</span>

  <span class="comment">// Number of bytes transferred so far.</span>
  <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span
                            class="identifier">bytes_transferred</span>
<span class="special">);</span>
</pre>
                <p>
                    A return value of 0 indicates that the read operation is complete.
                    A non-zero return value indicates the maximum number of bytes to
                    be read on the next call to the stream's read_some function.
                </p>
            </dd>
        </dl>
    </div>
    <h6>
        <a name="asio.reference.read.overload11.h1"></a>
        <span><a name="asio.reference.read.overload11.return_value"></a></span><a class="link"
                                                                                  href="overload11.html#asio.reference.read.overload11.return_value">Return
        Value</a>
    </h6>
    <p>
        The number of bytes transferred.
    </p>
    <h6>
        <a name="asio.reference.read.overload11.h2"></a>
        <span><a name="asio.reference.read.overload11.exceptions"></a></span><a class="link"
                                                                                href="overload11.html#asio.reference.read.overload11.exceptions">Exceptions</a>
    </h6>
    <div class="variablelist">
        <p class="title"><b></b></p>
        <dl>
            <dt><span class="term">asio::system_error</span></dt>
            <dd><p>
                Thrown on failure.
            </p></dd>
        </dl>
    </div>
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            <div class="copyright-footer">Copyright © 2003-2022 Christopher M. Kohlhoff<p>
                Distributed under the Boost Software License, Version 1.0. (See accompanying
                file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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